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Old 23rd January 2005, 02:07 AM   #1
extremy is offline extremy  United States
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Question Reading LC Meter,

I have a CircuitSpecialists LC meter.
On the dial I have 2mH, 20mH, 200mH, & 2H scales. I have no way to tell what to think about what the scales mean.
I wound up two inductors for a subwoofer, and quit when I got to the needed 18mH NS 9mH specs.
For the 18mH coil I get:
on the 2mH scale: 1.mH
on the 20mH scale: 17.55mH
on the 200mH scale: 17.4mH
on the 2H scale : .017H

For the 9mH coil I get:
on the 2mH scale: 1.mH
on the 20mH scale: 8.69mH
on the 200mH scale: 8.6mH
on the 2H scale: .008H

So, I don't know how to figure which scale is used when...

By searching the forum, on one link I found some mention of which scale to follow and so I hope to be close enough to the values I need. That person said use the 20mH scale

Looks like I may also use a small screw to mount the coils by the walnut core I used to wind on, and thereby increasing the inductance by a few points if needed. Shouldn't be necessary because the caps used are also +/- 20%, so things may adjust accordingly.

I read on one post about using old CD's for ends on a form. I tried it for my 18mH coil. Its hard to control movement on ends while winding. I used 4 cd's per end. With an 1/8" thick piece of fiberglass I have must better results because the fiberglass stays rigid.

What ya think?
GH
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Old 23rd January 2005, 02:12 AM   #2
extremy is offline extremy  United States
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Default me again,

me again,

This line, I wound up two inductors for a subwoofer, and quit when I got to the needed 18mH NS 9mH specs. <-- should read 18mH and 9mH.
I guess the ampersand sign isn't correct in forum-speak.

GH
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Old 23rd January 2005, 02:41 AM   #3
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Er, looks to me like the meter is working properly.

What exactly was your question?

Tim
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Old 23rd January 2005, 05:44 AM   #4
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Default Re: Reading LC Meter,

Quote:
Originally posted by extremy

on the 2mH scale: 1.mH
on the 20mH scale: 17.55mH
on the 200mH scale: 17.4mH
on the 2H scale : .017H
The 20mH, 200mH, and 2H scales are all giving the same reading (~17.5mH).

Its just the 2mH scale thats not right, im guessing it says 1.mH when its really anything over 2mH (out of range).

The 20mH scale should be the most accurate for the coils you are measuring.
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Old 23rd January 2005, 02:37 PM   #5
extremy is offline extremy  United States
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Default reference to scale,

Sch3mat1c,

I guess I would like to be able to qualify what the scale's titles mean.
So my question is really, what are the meanings behind,
2mH, 20mH, 200mH, 2H scales?

They've done the same scale scheme on the dial points for caps from
2 nF through 20uF.

Thanks,
GH
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Old 23rd January 2005, 02:57 PM   #6
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the scale needs to be larger than the measurement you are making... the closer the scale is to the actual measurement you are making, the more acurate the results.
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Old 23rd January 2005, 03:02 PM   #7
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Default Re: reference to scale,

Quote:
Originally posted by extremy

So my question is really, what are the meanings behind,
2mH, 20mH, 200mH, 2H scales?
They just mean the maximum value. So, the 2mH is for measuring inductance between 0 and 2mH. The 20mH is for 0 to 20mH. You can measure 1.5mH on the 20mH setting but with less accuracy than using the 2mH setting.
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Old 23rd January 2005, 03:15 PM   #8
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extremy
AudioFreak has pointed you in the right direction with his reply but he forgot to mention that you can't make a filter selection which is smaller than the value of the part or you will be 'out of scale'. The 1.mH reading you are getting on the 2mH scale is probably an overscale error. Read your meter manual to see how overscale errors are displayed to confirm our advice.
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Old 24th January 2005, 01:22 PM   #9
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yldouright,

I covered that by saying that the scale must be larger than the measurement you are making ... Bill explained it / worded it much better than I did.
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Old 24th January 2005, 01:29 PM   #10
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AudioFreak
Sorry, you were absolutely right, this time
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